Distributing device in plants for the maintenance of a dustfree, bacteriafree zone in a room

ABSTRACT

A distributing device in ventilating plants for the maintenance of a dust and bacteria free zone in a room by means of a number of air curtains surrounding the zone under simultaneous supply of ventilating air to said zone, said ventilating air then being discharged together with the air curtains, wherein means are arranged for a uniform distribution of the ventilating air, said means consisting of an inlet air channel terminating in a chamber of known type with an area essentially corresponding to that of the zone and containing a first perforated plate covering the entire area of the chamber, and being comparatively thick and having a low degree of perforation, and a second plate likewise covering the entire area of the chamber and preferably having a high degree of perforation and being comparatively thin, and wherein further means known per se are arranged for producing the air curtains surrounding said zone.

Unite States i tet 1 1 9 Lindestriim Apr. 10, 1973 541 DISTRIBUTlNG DEVICE IN PLANTS FOREIGN PATENTS OR APPLICATIONS [75] Inventor: Lars-Erik Lindestriim, .lonkoping,

Sweden [73] Assignee: Aktiebolaget Svenska Flaktfabriken,

Nacka, Sweden [22] Filed: June 23, 1971 [21] App1.No.: 155,786

[52] U.S. Cl ..98/36, 98/40 N, 239/553 [51] Int. Cl. ..F24f 9/00 [58] Field of Search ..239/590, 553; 34/224; 55/D1G. 29; 78/36, 40 D, 115 R, 40 C, 40 N [56] References Cited UNITED STATES PATENTS 3,511,162 5/1970 Truhan ..98/115RX 3,631,788 3/1970 Larkfeldt ..98/40 D 2,291,220 7/1942 Germonprez ...98/40 D X 3,308,741 3/1967 Chambers 1.98/40 D 3,580,008 4/1969 Barnard ....239/553.5 X 3,585,919 4/1969 Culpepper, .lr. ..98/33 R FOR THE MAINTENANCE OF A DUSTFREE, BACTERIAFREE ZONE TN A ROOM 312,656 7/1969 Sweden ..98/36 Primary ExaminerWilliam E. Wayner Attorney-1-1owson & Howson 5 7 ABSTRACT A distributing device in ventilating plants for the maintenance of a dust and bacteria free zone in a room by means of a number of air curtains surrounding the zone under simultaneous supply of ventilating air to said zone, said ventilating air then being discharged together with the air curtains, wherein means are arranged for a uniform distribution of the ventilating air, said means consisting of an inlet air channel terminating in a chamber of known type with an area essentially corresponding to that of the zone and containing a first perforated plate covering the entire area of the chamber, and being comparatively thick and having a low degree of perforation, and a second plate likewise covering the entire area of the chamber and preferably having a high degree of perforation and being comparatively thin, and wherein further means known per se are arranged for producing the air curtains surrounding said zone.

4 Claims, 2 Drawing Figures PATENTEU APR] 01973 DISTRIBUTING DEVICE IN PLANTS FOR THE MAHNTENANCE OF A DUSTFE, BACTEREAFREE ZQNE KN A ROOM This invention relates to a device for the maintenance of a dustfree, bacteriafree zone in a room by means of a number of air curtains surrounding the zone under simultaneous supply of ventilating air to the room within the curtained-off zone, the ventilating air then being discharged together with the air curtains.

The device according to the invention is intended especially for ventilation of rooms in which, owing for example to the risk of infection, extremely high requirements must be placed on the purity of the air in the actual enclosed area. High requirements on the purity of the air are now often placed not only in operating-theatres in hospitals but also for certain locations in the food industry and the chemical industry. Very important problems for satisfactory functioning of plant of such kind are that the ventilating air supply must be very uniformly distributed and correctly directed and that the rate of air flow in the zone in which personnel work within the screened-off area must not be so high as to be troublesome for the personnel or affect sensitive instruments, other problems being to obtain a uniform, equally distributed and entirely sealed air curtain without gaps. The object of the invention is to ensure a very uniform distribution and correct direction of the ventilating air supply.

The device according to the invention is characterized by means for ensuring a uniform distribution and direction of the ventilating air supplied within the zone at moderate rates of air flow, the means consisting of an inlet air channel terminating in a chamber of known type with an area essentially corresponding to that of the zone and containing a perforated plate covering the entire area of the chamber, said plate being comparatively thick and having a low degree of perforation, and a plate, likewise covering the entire area of the chamber, constituting the limiting surface facing the zone, preferably with high degree of perforation and comparatively thin, while the means for producing air curtains surrounding the zone consist of a separate distributing channel extending in a known manner around said chamber and connected to a separate inlet air channel, the distributing channel having on its surface facing the room one or more exhaust nozzles situated one beside the other so to produce a corresponding number of air curtains.

According to an expedient embodiment the firstmentioned plate with low degree of perforation, entirely covering the area of the chamber, consists of a plate 3-10 mm thick, preferably 5-8 mm. According to another advantageous embodiment, however, the plate may consist of relatively thin sheet metal on which is a surface having a number of parallel channels perpendicular to the plate. Another advantageous embodiment of the device is characterized in that, immediately adjoining the junction between the inlet air channel and the chamber of the zone, there is in the chamber a smaller, perforated distributing screen of an area rather larger than that of said inlet air channel for the chamber. To ensure satisfactory distribution of the air for the air curtains longitudinally along the distributing channel, and diversion of the air, the distributing channel for the air curtains, according to a suitable embodiment, is furnished with a strip extending nearly across the part of the distributing channel facing the room and extending along the length of the channel in such a way that, between said strip and one side-wall of the distributing channel, there is formed in said channel a slot considerably broader than the width of each exhaust nozzle.

As a result of this distribution and diversion the air does not obtain any speed component in the longitudinal direction of the slot and the air curtain becomes directed perpendicularly outwards and is of uniform strength. in supplementation of this arrangement, according to a further embodiment, there can be arranged in the space between an exhaust nozzle and the corresponding limiting wall of the distributing channel close to the exhaust nozzle an additional strip perpendicular to the first-named strip and extending a bit from the surface of the distributing channel facing the room towards the strip for forming a slot considerably broader than the width of each exhaust nozzle.

The invention will now be described with reference to the attached drawings showing an exemplifying embodiment of a device according to the invention, in which FIG. 1 shows in cross-section a schematic illustration of an air supply plant of the kind in question,

FIG. 2 shows in enlargement a corner of the plant within the dotted circle in the left-hand portion of FIG. 1.

In FIG. 1 items 5, 6, 7, 8, 9 and 10 are difierent parts of the means of the distributing device for ensuring a uniform distribution and correct direction of the ventilating air supplied within the zone at moderate rates of air flow. 5 is a chamber of area essentially corresponding to that of the zone. The ventilating air is supplied to this chamber through the inlet air channel 6. 7 is a smaller perforated distributing screen situated in the vicinity of said inlet air channel 6. The chamber 5 contains also two perforated plates 8 and 9, each of an area corresponding to the area of the chamber. The plate 8 is according to the invention comparatively thick, 3-10 mm, preferably 5-8 mm, and has a low degree of perforation, while plate 9 has a high degree of perforation and is comparatively thin. Through the combined effect of the perforated distributing screen 7 and the plates 8 and 9 the room is supplied with ventilating air in the desired manner. The function of the upper thick plate 8 is, with its low degree of perforation, to produce a relatively large drop of pressure to ensure a very good distribution and owing to its thickness direct the air vertically downwards. The same effect can be obtained by means of a plate consisting of relatively thin sheet metal on which is a surface having a number of parallel channels perpendicular to the plate. The function of the lower perforated plate 9 is to produce moderate rates of air flow in the zone in which personnel work, as a result of its larger free area. The means of the device for producing the air curtains surrounding the zone consist of the elements 1, 2a, 2b, 2c, 3, 4 in combination. The distributing channel 3 extends around the aforesaid chamber 5 and is connected to a separate inlet air channel 4. In the surface of the distributing channel 3 facing the room there are one or more (in the case shown two) exhaust nozzles l situated side by side designed to produce a corresponding number of air curtains. The distributing channel 3 has a strip 2a extending nearly across the part of the distributing channel facing the room and extending along the entire length of the channel. Beside one of said nozzles l, moreover, in the case shown, the distributing channel 3 may be provided with a longitudinal strip 2b of limited depth projecting into the channel and attached to the surface of the channel facing the room. In the embodiment here shown the two strips are situated at some distance from one another, so forging a longitudinal slot 2c. According to the invention this slot is made considerably broader than the width of each exhaust nozzle 1. A number of circular spacers are placed at regular intervals round the periphery of the distributing channel 3 for the assurance of an absolutely uniform slot of the nozzle 1. The circular shape of the spacers has proved valuable aerodynamically for preventing the air after passing through them from dividing and causing an opening in the air curtain. The use of spacers also permits a rapid, simple and exact assembly of the arrangement of slots in the manufacture of the device. The function of the aforesaid longitudinal slot, formed by the distributing plate 2a projecting towards the inner side wall of the chamber 3 is distribute the air longitudinally over the plate 2a and divert it via the slot to the nozzle (nozzles) 1. Owing to the distributing plate and the diversion the air, in passing through the nozzle (nozzles) 1, obtains no speed component in the longitudinal direction of the nozzle and the air curtain is therefore vertically directed and of uniform strength. In the case of this arrangement with two or more air curtains through nozzles l the spacers are staggered in relation to one another, as illustrated in my companion application, Ser. No. 155,972 filed concurrently herewith.

What I claimed is:

1. Distributing device in plants for the maintenance of a dustfree and bacteriafree zone in a room by means of a number of air curtains surrounding the zone under simultaneous supply of ventilating air to the room within the curtained-off zone, the ventilating air then being discharged together with the air curtains, characterized by means for a uniform distribution and direction of the ventilating air supplied within the zone at moderate rates of air flow, the means consisting of an inlet air channel terminating in a chamber with an area essentially corresponding to that of the zone and containing a perforated plate covering the entire area of the chamber, said plate being thick, in the range of 3 to 10 mm. thickness, and having a low degree of perforation, said perforation comprising narrow passages disposed perpendicular to the plane of said plate to produce a large pressure drop along with directing the air perpendicularly downward, and a second plate, coextensive with said first plate covering the entire area of the chamber, constituting the limiting surface facing the zone, said second plate having a high degree of perforation and being comparatively thin, the means for producing the air curtains surrounding the zone consisting of a separate distributing channel extending around said chamber and having a separate inlet air channel, the distributing channel having on its surface facing the room at least one exhaust nozzle situated to produce a, corresponding air urtain.

2. Device according to c am 1 wherein said first mentioned inlet air channel terminates in the chamber opposite to said thick perforated plate, and including in the chamber a smaller, perforated distributing screen of an area larger than that of said inlet air channel for the chamber to distribute the air from said channel across the entire area of said chamber.

3. Device according to claim 2, characterized in that the distributing channel for the air curtains is furnished with a strip extending nearly across the part of the distributing channel facing the room and extending along the length of the channel in such a way that, between said strip and one side-wall of the distributing channel, there is formed in said channel a slot considerably broader than the width of each exhaust nozzle.

4. Device according to claim 3, characterized in that, in the space between the exhaust nozzle and the slot of the distributing channel close to the exhaust nozzle there is a strip perpendicular to the first-named strip and extending a bit from the surface of the distributing channel facing the room towards the strip for forming a slot considerably broader than the width of each exhaust nozzle.

I UNITE STATES PATENT QFFICE QER'HFEQATE @F QEQ'HQN Patent No. 3 q 726 201;- Dated April 10, 1973 lnventofls) Lars-Erik Lindestrom It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading before [52] U.s 'cl., the following should be added:

[30] Foreign Application Priority Data July 1, 1970 SwedennMHHu,U916O/197O Column 3, lines 10-11, "forging" should be -forming-.

Signed and sealed this 18th day of December 1973.

(SEAL) Attest:

EDWARD MQPLETCHERJR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents FORM PC4050 USCOMM-DC scan-ps9 k (1,5. GOVERNMENT PRINT|NG OFFICE I959 0-366-334., 

1. Distributing device in plants for the maintenance of a dustfree and bacteriafree zone in a room by means of a number of air curtains surrounding the zone under simultaneous supply of ventilating air to the room within the curtained-off zone, the ventilating air then being discharged together with the air curtains, characterized by means for a uniform distribution and direction of the ventilating air supplied within the zone at moderate rates of air flow, the means consisting of an inlet air channel terminating in a chamber with an area essentially corresponding to that of the zone and containing a perforated plate covering the entire area of the chamber, said plate being thick, in the range of 3 to 10 mm. thickness, and having a low degree of perforation, said perforation comprising narrow passages disposed perpendicular to the plane of said plate to produce a large pressure drop along with directing the air perpendicularly downward, and a second plate, coextensive with said first plate covering the entire area of the chamber, constituting the limiting surface facing the zone, said second plate having a high degree of perforation and being comparatively thin, the means for producing the air curtains surrounding the zone consisting of a separate distributing channel extending around said chamber and having a separate inlet air channel, the distributing channel having on its surface facing the room at least one exhaust nozzle situated to produce a corresponding air curtain.
 2. Device according to claim 1 wherein said first mentioned inlet air channel terminates in the chamber opposite to said thick perforated platE, and including in the chamber a smaller, perforated distributing screen of an area larger than that of said inlet air channel for the chamber to distribute the air from said channel across the entire area of said chamber.
 3. Device according to claim 2, characterized in that the distributing channel for the air curtains is furnished with a strip extending nearly across the part of the distributing channel facing the room and extending along the length of the channel in such a way that, between said strip and one side-wall of the distributing channel, there is formed in said channel a slot considerably broader than the width of each exhaust nozzle.
 4. Device according to claim 3, characterized in that, in the space between the exhaust nozzle and the slot of the distributing channel close to the exhaust nozzle there is a strip perpendicular to the first-named strip and extending a bit from the surface of the distributing channel facing the room towards the strip for forming a slot considerably broader than the width of each exhaust nozzle. 